private Image GetCropedImage(Image imgSource, int width, int height)
{
bool isSizeChanged = false;
// 計算截圖範圍
int cropWidth = imgSource.Width;
int cropHeight = imgSource.Height;
if (width < imgSource.Width && height < imgSource.Height)
{
if (1.0 * imgSource.Width / width * height <= imgSource.Height)
{
cropHeight = (int)(1.0 * imgSource.Width / width * height);
isSizeChanged = true;
}
else if (1.0 * imgSource.Height / height * width <= imgSource.Width)
{
cropWidth = (int)(1.0 * imgSource.Height / height * width);
isSizeChanged = true;
}
}
else if (width < imgSource.Width && height >= imgSource.Height)
{
cropWidth = (int)(1.0 * imgSource.Height / height * width);
isSizeChanged = true;
}
else if (width >= imgSource.Width && height < imgSource.Height)
{
cropHeight = (int)(1.0 * imgSource.Width / width * height);
isSizeChanged = true;
}
else
{
// 原圖
}
// 進行截圖及縮圖
if (isSizeChanged)
{
var cropedImage = ImageResizer.Crop(imgSource, cropWidth, cropHeight, AnchorPosition.Center);
return(ImageResizer.ScaleByFixedSize(cropedImage, width, height));
}
return(null);
}
public virtual async Task <bool> GenerateAsync(string imageUrl, bool isRegenerateAll)
{
if (string.IsNullOrEmpty(imageUrl))
{
throw new ArgumentNullException("imageUrl");
}
var thumbnailsParameters = GetThumbnailParameters();
if (thumbnailsParameters.IsNullOrEmpty())
{
return(false);
}
var originalImage = await LoadImageAsync(imageUrl);
var format = GetImageFormat(originalImage);
foreach (var parameters in thumbnailsParameters)
{
var thumbnailUrl = AddAliasToImageUrl(imageUrl, parameters.Alias);
if (isRegenerateAll || !Exists(thumbnailUrl))
{
//one process only can use an Image object at the same time.
Image clone;
lock (_progressLock)
{
clone = (Image)originalImage.Clone();
}
//Generate a Thumbnail
Image thumbnail = null;
switch (parameters.Method)
{
case ResizeMethod.FixedSize:
thumbnail = ImageResizer.FixedSize(clone, parameters.Width, parameters.Height, parameters.Color);
break;
case ResizeMethod.FixedWidth:
thumbnail = ImageResizer.FixedWidth(clone, parameters.Width, parameters.Color);
break;
case ResizeMethod.FixedHeight:
thumbnail = ImageResizer.FixedHeight(clone, parameters.Height, parameters.Color);
break;
case ResizeMethod.Crop:
thumbnail = ImageResizer.Crop(clone, parameters.Width, parameters.Height, parameters.AnchorPosition);
break;
}
//Save
if (thumbnail != null)
{
SaveImage(thumbnailUrl, thumbnail, format);
}
else
{
throw new ThumbnailGenetationException(string.Format(CultureInfo.InvariantCulture, "Cannot generate thumbnail for image '{0}'.", thumbnailUrl));
}
}
}
return(true);
}
